Electroluminescent iridium compounds with fluorinated phenylpyridines, phenylpyrimidines, and phenylquinolines and devices made with such compounds

ABSTRACT

The present invention is generally directed to electroluminescent Ir(III) compounds, the substituted 2-phenylpyridines, phenylpyrimidines, and phenylquinolines that are used to make the Ir(III) compounds, and devices that are made with the Ir(III) compounds.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to electroluminescent complexes ofiridium(III) with fluorinated phenylpyridines, phenylpyrimidines, andphenylquinolines. It also relates to electronic devices in which theactive layer includes an electroluminescent Ir(III) complex.

[0003] 2. Description of the Related Art

[0004] Organic electronic devices that emit light, such aslight-emitting diodes that make up displays, are present in manydifferent kinds of electronic equipment. In all such devices, an organicactive layer is sandwiched between two electrical contact layers. Atleast one of the electrical contact layers is light-transmitting so thatlight can pass through the electrical contact layer. The organic activelayer emits light through the light-transmitting electrical contactlayer upon application of electricity across the electrical contactlayers.

[0005] It is well known to use organic electroluminescent compounds asthe active component in light-emitting diodes. Simple organic moleculessuch as anthracene, thiadiazole derivatives, and coumarin derivativesare known to show electroluminescence. Semiconductive conjugatedpolymers have also been used as electroluminescent components, as hasbeen disclosed in, for example, Friend et al., U.S. Pat. No. 5,247,190,Heeger et al., U.S. Pat. No. 5,408,109, and Nakano et al., PublishedEuropean Patent Application 443 86 1. Complexes of 8-hydroxyquinolatewith trivalent metal ions, particularly aluminum, have been extensivelyused as electroluminescent components, as has been disclosed in, forexample, Tang et al., U.S. Pat. No. 5,552,678.

[0006] Burrows and Thompson have reported thatfac-tris(2-phenylpyridine) iridium can be used as the active componentin organic light-emitting devices. (Appl. Phys. Lett. 1999, 75, 4.) Theperformance is maximized when the iridium compound is present in a hostconductive material. Thompson has further reported devices in which theactive layer is poly(N-vinyl carbazole) doped withfac-tris[2-(4′,5′-difluorophenyl)pyridine-C′²,N]iridium(III). (PolymerPreprints 2000, 41(1), 770.)

[0007] However, there is a continuing need for electroluminescentcompounds having improved efficiency.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to an iridium compound(generally referred as “Ir(III) compounds”) having at least two2-phenylpyridine ligands in which there is at least one fluorine orfluorinated group on the ligand. The iridium compound has the followingFirst Formula:

IrL^(a)L^(b)L^(c) _(x)L′_(y)L″_(z)  (First Formula)

[0009] where:

[0010] x=0 or 1, y=0, 1 or 2, and z=0 or 1, with the proviso that:

[0011] x=0 or y+z=0 and

[0012] when y=2 then z=0;

[0013] L′=a bidentate ligand or a monodentate ligand, and is not aphenylpyridine, phenylpyrimidine, or phenylquinoline; with the provisothat:

[0014] when L′ is a monodentate ligand, y+z=2, and

[0015] when L′ is a bidentate ligand, z=0;

[0016] L″=a monodentate ligand, and is not a phenylpyridine, andphenylpyrimidine, or phenylquinoline; and

[0017] L^(a), L^(b) and L^(c) are alike or different from each other andeach of L^(a), L^(b) and L^(c) has structure (I) below:

[0018] wherein:

[0019] adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring,

[0020] at least one of R₁-R₈ is selected from F, C_(n)F_(2n+1),OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, or Br, and

[0021] A=C or N, provided that when A=N, there is no R₁.

[0022] In another embodiment, the present invention is directed tosubstituted 2-phenylpyridine, phenylpyrimidine, and phenylquinolineprecursor compounds from which the above Ir(III) compounds are made. Theprecursor compounds have a structure (II) or (III) below:

[0023] where A and R₁-R₈ are as defined in structure (I) above, and R₉is H.

[0024] where:

[0025] at least one of R₁₀-R₁₉ is selected from F, C_(n)F_(2n+1),OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, or Br, and R₂₀ is H.

[0026] It is understood that there is free rotation about thephenyl-pyridine, phenyl-pyrimidine and the phenyl-quinoline bonds.However, for the discussion herein, the compounds will be described interms of one orientation.

[0027] In another embodiment, the present invention is directed to anorganic electronic device having at least one emitting layer comprisingthe above Ir(III) compound, or combinations of the above Ir(III)compounds.

[0028] As used herein, the term “compound” is intended to mean anelectrically uncharged substance made up of molecules that furtherconsist of atoms, wherein the atoms cannot be separated by physicalmeans. The term “ligand” is intended to mean a molecule, ion, or atomthat is attached to the coordination sphere of a metallic ion. The term“complex”, when used as a noun, is intended to mean a compound having atleast one metallic ion and at least one ligand. The term “group” isintended to mean a part of a compound, such a substituent in an organiccompound or a ligand in a complex. The term “facial” is intended to meanone isomer of a complex, Ma₃b₃, having octahedral geometry, in which thethree “a” groups are all adjacent, i.e. at the corners of one face ofthe octahedron. The term “meridional” is intended to mean one isomer ofa complex, Ma₃b₃, having octahedral geometry, in which the three “a”groups occupy three positions such that two are trans to each other. Thephrase “adjacent to,” when used to refer to layers in a device, does notnecessarily mean that one layer is immediately next to another layer. Onthe other hand, the phrase “adjacent R groups,” is used to refer to Rgroups that are next to each other in a chemical formula (i.e., R groupsthat are on atoms joined by a bond). The term “photoactive” refers toany material that exhibits electroluminescence and/or photosensitivity.

DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a schematic diagram of a light-emitting device (LED).

[0030]FIG. 2 is a schematic diagram of an LED testing apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The Ir(III) compounds of the invention have the First FormulaIr(III)L^(a)L^(b)L^(c) _(x)L′_(y) above.

[0032] The above Ir(III) compounds are frequently referred to ascyclometalated complexes: Ir(III) compounds having the following SecondFormula is also frequently referred to as a bis-cyclometalated complex.:

IrL^(a)L^(b)L′_(y)L″_(z)  (Second Formula)

[0033] where:

[0034] y, z, L^(a), L^(b), L′, and L″ are as defined in the FirstFormula above.

[0035] Ir(III) compounds having the following Third Formula is alsofrequently referred to as a tris-cyclometalated complex.:

IrL^(a)L^(b)L^(c)  (Third Formula)

[0036] where:

[0037] L^(a), L^(b) and L^(c) are as defined in the First Formuladescribed above.

[0038] The preferred cyclometalated complexes are neutral and non-ionic,and can be sublimed intact. Thin films of these materials obtained viavacuum deposition exhibit good to excellent electroluminescentproperties. Introduction of fluorine substituents into the ligands onthe iridium atom increases both the stability and volatility of thecomplexes. As a result, vacuum deposition can be carried out at lowertemperatures and decomposition of the complexes can be avoided.Introduction of fluorine substituents into the ligands can often reducethe non-radiative decay rate and the self-quenching phenomenon in thesolid state. These reductions can lead to enhanced luminescenceefficiency. Variation of substituents with electron-donating andelectron-withdrawing properties allows for fine-tuning ofelectroluminescent properties of the compound and hence optimization ofthe brightness and efficiency in an electroluminescent device.

[0039] While not wishing to be bound by theory, it is believed that theemission from the iridium compounds is ligand-based, resulting frommetal-to-ligand charge transfer. Therefore, compounds that can exhibitelectroluminescence include those of compounds of the Second FormulaIrL^(a)L^(b)L′_(y)L″_(z) above, and the Third Formula IrL^(a)L^(b)L^(c)above, where all L^(a), L^(b), and L^(c) in the Third Formula arephenylpyridines, phenylpyrimidines, or phenylquinolines. The R₁-R₈groups of structures (I) and (II), and the R₁₀-R₁₉ groups of structure(III) above may be chosen from conventional substitutents for organiccompounds, such as alkyl, alkoxy, halogen, nitro, and cyano groups, aswell as fluoro, fluorinated alkyl and fluorinated alkoxy groups. Thegroups can be partially or fully fluorinated (perfluorinated). Preferrediridium compounds have all R₁-R₈ and R₁₀-R₁₉ substituents selected fromfluoro, perfluorinated alkyl (C_(n)F_(2n+1)) and perfluorinated alkoxygroups (OC_(n)F_(2n+1)), where the perfluorinated alkyl and alkoxygroups have 1-6 carbon atoms, or a group of the formula OCF₂X, whereX=H, Cl, or Br.

[0040] It has been found that the electroluminescent properties of thecyclometalated iridium complexes are poorer when any one or more of theR₁-R₈ and R₁₀-R₁₉ groups is a nitro group. Therefore, it is preferredthat none of the R₁-R₈ and R₁₀-R₁₉ groups is a nitro group.

[0041] The nitrogen-containing ring can be a pyridine ring, a pyrimidineor a quinoline. It is preferred that at least one fluorinatedsubstituent is on the nitrogen-containing ring; most preferably CF₃.

[0042] Any conventional ligands known to transition metal coordinationchemistry is suitable as the L′ and L″ ligands. Examples of bidentateligands include compounds having two coordinating groups, such asethylenediamine and acetylacetonate, which may be substituted. Examplesof monodentate ligands include chloride and nitrate ions andmono-amines. It is preferred that the iridium complex be neutral andsublimable. If a single bidentate ligand is used, it should have a netcharge of minus one (−1). If two monodentate ligands are used, theyshould have a combined net charge of minus one (−1). Thebis-cyclometalated complexes can be useful in preparingtris-cyclometalated complexes where the ligands are not all the same.

[0043] In a preferred embodiment, the iridium compound has the ThirdFormula IrL^(a)L^(b)L^(c) as described above.

[0044] In a more preferred embodiment, L^(a)=L^(b)=L^(c). These morepreferred compounds frequently exhibit a facial geometry, as determinedby single crystal X-ray diffraction, in which the nitrogen atomscoordinated to the iridium are trans with respect to carbon atomscoordinated to the iridium. These more preferred compounds have thefollowing Fourth Formula:

fac−Ir(L^(a))₃  (Fourth Formula)

[0045] where L^(a) has structure (I) above.

[0046] The compounds can also exhibit a meridional geometry in which twoof the nitrogen atoms coordinated to the iridium are trans to eachother. These compounds have the following Fifth Formula:

mer−Ir(L^(a))₃  (Fifth Formula)

[0047] where L^(a) has structure (1) above.

[0048] Examples of compounds of the Fourth Formula and Fifth Formulaabove are given in Table I below: TABLE 1 Com- pound A R₁ R₂ R₃ R₄ R₅ R₆R₇ R₈ Formula 1-a C H H CF₃ H H H H H Fourth 1-b C H H CF₃ H H H F HFourth 1-c C H H CF₃ H F H H H Fourth 1-d C H H H H F H H H Fourth 1-e CH H CF₃ H H CF₃ H H Fourth 1-f C H H H H H CF₃ H H Fourth 1-g C H H H HH H F H Fourth 1-h C Cl H CF₃ H H H H H Fourth 1-i C H H CF₃ H H H OCH₃H Fourth 1-j C H H CF₃ H H F H H Fourth 1-k C H H NO₂ H H CF3 H H Fourth1-l C H H CF₃ H H H OCF₃ H Fourth 1-m N — CF₃ H H H H F H Fourth 1-q C HH CF₃ H H OCH₃ H H Fourth 1-r C H OCH₃ H H H H CF₃ H Fourth 1-s C H H HH F H F H Fourth and Fifth 1-t C H H CF₃ H H F H F Fifth 1-u C H H CF₃ HF H F H Fifth 1-v C H H CF₃ H H H F H Fifth

[0049] Examples compounds of the Second Formula IrL^(a)L^(b)L′_(y)L″_(z)above include compounds 1-n, 1-o, 11-w and 1-x, respectively havingstructure (IV), (V), (VI), (IX) and (X) below:

[0050] The iridium complexes of the Third Formula IrL^(a)L^(b)L^(c)above are generally prepared from the appropriate substituted2-phenylpyridine, phenylpyrimidine, or phenylquinoline. The substituted2-phenylpyridines, phenylpyrimidines, and phenylquinolines, as shown inStructure (II) above, are prepared, in good to excellent yield, usingthe Suzuki coupling of the substituted 2-chloropyridine,2-chloropyrimidine or 2-chloroquinoline with arylboronic acid asdescribed in 0. Lohse, P.Thevenin, E. Waldvogel Synlett, 1999, 45-48.This reaction is illustrated for the pyridine derivative, where X and Yrepresent substituents, in Equation (1) below:

[0051] Examples of 2-phenylpyridine and 2-phenylpyrimidine compounds,having structure (II) above, are given in Table 2 below: TABLE 2Compound A R₁ R₂ R₃ R₄ R₅ R₆ R₇ R₈ R₉ 2-a C H H CF₃ H F H H H H 2-b C HH CF₃ H H CF₃ H H H 2-c C H H NO₂ H H CF₃ H H H 2-d C H H CF₃ H H F H HH 2-e C H H CF₃ H H H CH₃O H H 2-f C Cl H CF₃ H H H H H H 2-g C H H HCF₃ H H F H H 2-h N — H H H H H F H H 2-i C H H CF₃ H H H CF₃O H H 2-j N— CF₃ H H F H H H H 2-k C H H CF₃ H H H F H H 2-l C CF₃ H H H H H H H H2-m C Cl H CF₃ H H H F H H 2-n C CF₃ H H H H H F H H 2-o C CF₃ H H H H HCH₃O H H 2-p C Cl H CF₃ H H H CH₃O H H 2-q N — CF₃ H H H H F H H 2-r CCl H CF₃ H H H H H F 2-s C H H CF₃ H H H H H H 2-t C Cl H H H F H H H H2-v C H H CF₃ H H CH₃O H H H 2-w C H CH₃O H H H H CF₃ H H 2-x C H H H HH F F H H 2-y C H H CF₃ H H F H F H 2-z C H H CF₃ H F H F H H 2-aa C H HBr H H H Br H H

[0052] One example of a substituted 2-phenylquinoline compound, havingstructure (III) above, is compound 2-u, which has R₁₇=CF₃ and R₁₀-R₁₆and R₁₈-R₂₀=H.

[0053] The 2-phenylpyridines, pyrimidines, and quinolines thus preparedare used for the synthesis of the cyclometalated iridium complexes. Aconvenient one-step method has been developed employing commerciallyavailable iridium trichloride hydrate and silver trifluoroacetate. Thereactions are generally carried out with an excess of 2-phenylpyridine,pyrimidine, or quinoline, without a solvent, in the presence of 3equivalents of AgOCOCF₃. This reaction is illustrated for a2-phenylpyridine in Equation (2) below:

[0054] The tris-cyclometalated iridium complexes were isolated,purified, and fully characterized by elemental analysis, ¹H and ¹⁹F NMRspectral data, and, for compounds 1-b, 1-c, and 1-e, single crystalX-ray diffraction. In some cases, mixtures of isomers are obtained.Often the mixture can be used without isolating the individual isomers.

[0055] The iridium complexes having the Second FormulaIrL^(a)L^(b)L′_(y)L″_(z) above, may, in some cases, be isolated from thereaction mixture using the same synthetic procedures as preparing thosehaving Third Formula IrL^(a)L^(b)L^(c) above. The complexes can also beprepared by first preparing an intermediate iridium dimer havingstructure VII below:

[0056] wherein:

[0057] B=H, CH₃, or C₂H₅, and

[0058] L^(a), L^(b),L^(c), and L^(d) can be the same or different fromeach other and each of L^(a), L^(b),L^(c), and L^(d) has structure (I)above.

[0059] The iridium dimers can generally be prepared by first reactingiridium trichloride hydrate with the 2-phenylpyridine, phenylpyrimidineor phenylquinoline, and adding NaOB.

[0060] One particularly useful iridium dimer is the hydroxo iridiumdimer, having structure VIII below:

[0061] This intermediate can be used to prepare compound 1-p by theaddition of ethyl acetoacetate.

[0062] Electronic Device

[0063] The present invention also relates to an electronic devicecomprising at least one photoactive layer positioned between twoelectrical contact layers, wherein the at least one layer of the deviceincludes the iridium complex of the invention. Devices frequently haveadditional hole transport and electron transport layers. A typicalstructure is shown in FIG. 1. The device 100 has an anode layer 110 anda cathode layer 150. Adjacent to the anode is a layer 120 comprisinghole transport material. Adjacent to the cathode is a layer 140comprising an electron transport material. Between the hole transportlayer and the electron transport layer is the photoactive layer 130.

[0064] Depending upon the application of the device 100, the photoactivelayer 130 can be a light-emitting layer that is activated by an appliedvoltage (such as in a light-emitting diode or light-emittingelectrochemical cell), a layer of material that responds to radiantenergy and generates a signal with or without an applied bias voltage(such as in a photodetector). Examples of photodetectors includephotoconductive cells, photoresistors, photoswitches, phototransistors,and phototubes, and photovoltaic cells, as these terms are describe inMarkus, John, Electronics and Nucleonics Dictionary, 470 and 476(McGraw-Hill, Inc. 1966).

[0065] The iridium compounds of the invention are particularly useful asthe photoactive material in layer 130, or as electron transport materialin layer 140. Preferably the iridium complexes of the invention are usedas the light-emitting material in diodes. It has been found that inthese applications, the fluorinated compounds of the invention do notneed to be in a solid matrix diluent in order to be effective. A layerthat is greater than 20% by weight iridium compound, based on the totalweight of the layer, up to 100% iridium compound, can be used as theemitting layer. This is in contrast to the non-fluorinated iridiumcompound, tris(2-phenylpyridine) iridium (III), which was found toachieve maximum efficiency when present in an amount of only 6-8% byweight in the emitting layer. This was necessary to reduce theself-quenching effect. Additional materials can be present in theemitting layer with the iridium compound. For example, a fluorescent dyemay be present to alter the color of emission. A diluent may also beadded. The diluent can be a polymeric material, such as poly(N-vinylcarbazole) and polysilane. It can also be a small molecule, such as4,4′-N,N′-dicarbazole biphenyl or tertiary aromatic amines. When adiluent is used, the iridium compound is generally present in a smallamount, usually less than 20% by weight, preferably less than 10% byweight, based on the total weight of the layer.

[0066] In some cases the iridium complexes may be present in more thanone isomeric form, or mixtures of different complexes may be present. Itwill be understood that in the above discussion of OLEDs, the term “theiridium compound” is intended to encompass mixtures of compounds and/orisomers.

[0067] To achieve a high efficiency LED, the HOMO (highest occupiedmolecular orbital) of the hole transport material should align with thework function of the anode, the LUMO (lowest un-occupied molecularorbital) of the electron transport material should align with the workfunction of the cathode. Chemical compatibility and sublimation temp ofthe materials are also important considerations in selecting theelectron and hole transport materials.

[0068] The other layers in the OLED can be made of any materials whichare known to be useful in such layers. The anode 110, is an electrodethat is particularly efficient for injecting positive charge carriers.It can be made of, for example materials containing a metal, mixedmetal, alloy, metal oxide or mixed-metal oxide, or it can be aconducting polymer. Suitable metals include the Group 11 metals, themetals in Groups 4, 5, and 6, and the Group 8-10 transition metals. Ifthe anode is to be light-transmitting, mixed-metal oxides of Groups 12,13 and 14 metals, such as indium-tin-oxide, are generally used. TheIUPAC numbering system is used throughout, where the groups from thePeriodic Table are numbered from left to right as I-18 (CRC Handbook ofChemistry and Physics, 81^(st) Edition, 2000). The anode 110 may alsocomprise an organic material such as polyaniline as described in“Flexible light-emitting diodes made from soluble conducting polymer,”Nature vol. 357, pp 477-479 (Jun. 11, 1992). At least one of the anodeand cathode should be at least partially transparent to allow thegenerated light to be observed.

[0069] Examples of hole transport materials for layer 120 have beensummarized for example, in Kirk-Othmer Encyclopedia of ChemicalTechnology, Fourth Edition, Vol. 18, p. 837-860, 1996, by Y. Wang. Bothhole transporting molecules and polymers can be used. Commonly used holetransporting molecules are:N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis-(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),a-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)-benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane(DCZB), N,N,N′,N′-tetrakis(4-methyl-phenyl)-(1,1′-biphenyl)-4,4′-diamine(TTB), and porphyrinic compounds, such as copper phthalocyanine.Commonly used hole transporting polymers are polyvinylcarbazole,(phenylmethyl)polysilane, and polyaniline. It is also possible to obtainhole transporting polymers by doping hole transporting molecules such asthose mentioned above into polymers such as polystyrene andpolycarbonate.

[0070] Examples of electron transport materials for layer 140 includemetal chelated oxinoid compounds, such astris(8-hydroxyquinolato)aluminum (Alq₃); phenanthroline-based compounds,such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA) or4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) and3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ).Layer 140 can function both to facilitate electron transport, and alsoserve as a buffer layer or confinement layer to prevent quenching of theexciton at layer interfaces. Preferably, this layer promotes electronmobility and reduces exciton quenching.

[0071] The cathode 150, is an electrode that is particularly efficientfor injecting electrons or negative charge carriers. The cathode can beany metal or nonmetal having a lower work function than the anode.Materials for the cathode can be selected from alkali metals of Group 1(e.g., Li, Cs), the Group 2 (alkaline earth) metals, the Group 12metals, including the rare earth elements and lanthanides, and theactinides. Materials such as aluminum, indium, calcium, barium, samariumand magnesium, as well as combinations, can be used. Li-containingorganometallic compounds can also be deposited between the organic layerand the cathode layer to lower the operating voltage.

[0072] It is known to have other layers in organic electronic devices.For example, there can be a layer (not shown) between the conductivepolymer layer 120 and the active layer 130 to facilitate positive chargetransport and/or band-gap matching of the layers, or to function as aprotective layer. Similarly, there can be additional layers (not shown)between the active layer 130 and the cathode layer 150 to facilitatenegative charge transport and/or band-gap matching between the layers,or to function as a protective layer. Layers that are known in the artcan be used. In addition, any of the above-described layers can be madeof two or more layers. Alternatively, some or all of inorganic anodelayer 110, the conductive polymer layer 120, the active layer 130, andcathode layer 150, may be surface treated to increase charge carriertransport efficiency. The choice of materials for each of the componentlayers is preferably determined by balancing the goals of providing adevice with high device efficiency.

[0073] It is understood that each functional layer may be made up ofmore than one layer.

[0074] The device can be prepared by sequentially vapor depositing theindividual layers on a suitable substrate. Substrates such as glass andpolymeric films can be used. Conventional vapor deposition techniquescan be used, such as thermal evaporation, chemical vapor deposition, andthe like. Alternatively, the organic layers can be coated from solutionsor dispersions in suitable solvents, using any conventional coatingtechnique. In general, the different layers will have the followingrange of thicknesses: anode 110, 500-5000 Å, preferably 1000-2000 Å;hole transport layer 120, 50-1000 Å, preferably 200-800 Å;light-emitting layer 130, 10-1000 Å, preferably 100-800 Å; electrontransport layer 140, 50-1000 Å, preferably 200-800 Å; cathode 150,200-10000 Å, preferably 300-5000 Å. The location of the electron-holerecombination zone in the device, and thus the emission spectrum of thedevice, can be affected by the relative thickness of each layer. Thusthe thickness of the electron-transport layer should be chosen so thatthe electron-hole recombination zone is in the light-emitting layer. Thedesired ratio of layer thicknesses will depend on the exact nature ofthe materials used.

[0075] It is understood that the efficiency of devices made with theiridium compounds of the invention, can be further improved byoptimizing the other layers in the device. For example, more efficientcathodes such as Ca, Ba or LiF can be used. Shaped substrates and novelhole transport materials that result in a reduction in operating voltageor increase quantum efficiency are also applicable. Additional layerscan also be added to tailor the energy levels of the various layers andfacilitate electroluminescence.

[0076] The iridium complexes of the invention often are phosphorescentand photoluminescent and may be useful in applications other than OLEDs.For example, organometallic complexes of iridium have been used asoxygen sensitive indicators, as phosphorescent indicators in bioassays,and as catalysts. The bis cyclometalated complexes can be used tosythesize tris cyclometalated complexes where the third ligand is thesame or different.

EXAMPLES

[0077] The following examples illustrate certain features and advantagesof the present invention. They are intended to be illustrative of theinvention, but not limiting. All percentages are by weight, unlessotherwise indicated.

Example 1

[0078] This example illustrates the preparation of the 2-phenylpyridinesand 2-phenylpyrimidines which are used to form the iridium compounds.

[0079] The general procedure used was described in O. Lohse, P.Thevenin, E. Waldvogel Synlett, 1999, 45-48. In a typical experiment, amixture of 200 ml of degassed water, 20 g of potassium carbonate, 150 mlof 1,2-dimethoxyethane, 0.5 g of Pd(PPh₃)₄, 0.05 mol of a substituted2-chloropyridine (quinoline or pyrimidine) and 0.05 mol of a substitutedphenylboronic acid was refluxed (80-90° C.) for 16-30 h. The resultingreaction mixture was diluted with 300 ml of water and extracted withCH₂Cl₂ (2×100 ml). The combined organic layers were dried over MgSO₄,and the solvent removed by vacuum. The liquid products were purified byfractional vacuum distillation. The solid materials were recrystallizedfrom hexane. The typical purity of isolated materials was >98%. Thestarting materials, yields, melting and boiling points of the newmaterials are given in Table 3. NMR data and analytical data are givenin Table 4. TABLE 3 Preparation of 2-Phenyl Pyridines, Phenylpyrimidinesand Phenylquinolines Compound Yield in % B.p./mm Hg (m.p.) in ° C. 2-s70 — 2-a 72 — 2-b 48 — 2-u 75 (76-78) 2-c 41 (95-96) 2-d 38 (39-40) 2-e55 74.5/0.1  2-g 86  71-73/0.07  2-t 65  77-78/0.046  2-k 50 (38-40) 2-m80  72-73/0.01  2-f 22  52-33/0.12  2-v 63 95-96/13   2-w 72 2-x 35 61-62/0.095  2-y 62 (68-70) 2-z 42  66-67/0.06  (58-60) 2-aa 60

[0080] TABLE 4 Properties of 2-Phenyl Pyridines, Phenylpyrimidines andPhenylquinolines Analysis %, found Compound ¹H NMR ¹⁹F NMR (calc.) or MS(M⁺) 2-s 7.48 (3H), −62.68 C, 64.50 (64.57) 7.70 (1H), H, 3.49 (3.59)7.83 (1H), N, 6.07 (6.28) 7.90 (2H), 8.75 (1H) 2-a 7.19 (1H), −60.82(3F, s), C, 59.56 (59.75) 7.30 (1H), −116.96 (1F, m) H, 3.19 (2.90) 7.43(1H), N, 5.52 (5.81) 7.98 (2H), 8.07 (1H) 9.00 (1H) 2-b 7.58 (1H),−62.75 (3F, s), C, 53.68 (53.60) 7.66 (1H), −63.10 (3F, s) H, 2.61(2.40) 7.88 (1H), N, 4.53 (4.81) 8.03 (1H), 8.23 (1H), 8.35 (1H)  8.99(1H)  2-u 7.55 (1H), −62.89 (s) C, 69.17 (70.33) 7.63 (1H), H, 3.79(3.66) 7.75 (2H), N, 4.88 (5.12) 7.89 (2H), 8.28 (2H), 8.38 (1H), 8.50(1H) 2-c 7.53 (1H), −62.14 (s) C, 53.83 (53.73) 7.64 (1H), H, 2.89(2.61) 7.90 (1H), N, 9.99 (10.44) 8.18 (1H), 8.30 (1H), 8.53 (1H), 9.43(1H)  2-d 7.06 (1H), −62.78 (3F, s), C, 59.73 (59.75) 7.48 (1H), −112.61(1F, m) H, 2.86 (2.90) 7.81 (3H), N, 5.70 (5.81) 8.01 (1H), 8.95 (1H),2-e 3.80 (3H)  −62.63 (s) C, 61.66 (61.90) 6.93 (2H), H, 3.95 (4.04)7.68 (1H), N, 5.53 (5.38) 7.85 (1H), 7.96 (2H), 8.82 (1H), 2-g 2.70(3H)  −114.03 (m) C, 76.56 (77.00) 7.10 (3H), H, 5.12 (5.30) 7.48 (1H),N, 5.43 (7.50) 7.60 (1H), 8.05 (2H), 2-t 7.10 (2H), −62.73 (3F, s) C,50.51 (52.17) 7.35 (2H), −113.67 (1F, m) H, 1.97 (2.17) 7.96 (1H), N,5.09 (5.07) 8.78 (1H), 2-k 7.08 (2H), −62.75 (3F, s) C, 60.39 (59.75),7.62 (1H), −111.49 (m) H, 3.38 (2.90), 7.90 (3H), N, 5.53 (5.51) 8.80(1H), 2-m 7.10 (2H), −62.63 (3F, s) C, 52.13 (52.17) 7.80 (2H), −111.24(m) H, 2.16 (2.17) 8.00 (1H), N, 4.85 (5.07) 8.75 (1H), 2-f 7.55 (3H),−62.57 (s) 257 (M⁺, 7.77 (2H), C₁₂H₇F₃ClN⁺), 8.06 (1H), 222 (M—Cl) 8.87(1H)  2-v 3.8 (3H), −62.70 ppm C, 61.66 (61.37), 6.95 (1H), H, 3.98(3.67), 7.30 (1H), N, 5.53 (5.48) 7.50 (1H), 7.58 (1H), 7.75 (1H), 7.90(1H), 8.87 (1H) 2-w 8.54 (1H, d), −63.08 (3F, s) 8.21 (2H, d), 7.70 (2H,d), 7.24 (1H, s), 6.82 (1H, dd), 3.91 (3H, s) 2-x 6.9 (2H, m), −109.70(1F, m), 7.18 (2H, m), −113.35 (1F, m). 7.68 (2H, m), 7.95 (1H, m), 8.65(1H, m); 6.94 (1H), −62.72 (3F, s), 7.62 (2H), −109.11 (2F, m) 7.82(1H), 8.03 (1H), 8.96 (1H); 2-z 6.85 (1H), −62.80 (3F, s), 6.93 (1H),−107.65 (1F, m), 7.80, 7.90, −112.45 (1F, m). 8.05 (3H), 8.89 (1H); 2-aa7.70 (3H, m), 7.85 (3H, m), 7.80, 7.90, 8.85 (1H, m).

Example 2

[0081] This example illustrates the preparation of iridium compounds ofthe Fourth Formula fac-Ir(L^(a))₃ above.

[0082] In a typical experiment, a mixture of IrCl₃.nH₂O (53-55% Ir),AgOCOCF₃ (3.1 equivalents per Ir), 2-arylpyridine (excess), and(optionally) a small amount of water was vigorously stirred under N₂ at180-195° C. (oil bath) for 2-8 hours. The resulting mixture wasthoroughly extracted with CH₂Cl₂ until the extracts were colorless. Theextracts were filtered through a silica column to produce a clear yellowsolution. Evaporation of this solution gave a residue which was treatedwith methanol to produce colored crystalline tris-cyclometalated Ircomplexes. The complexes were separated by filtration, washed withmethanol, dried under vacuum, and (optionally) purified bycrystallization, vacuum sublimation, or Soxhlet extraction. Yields:10-82%. All materials were characterized by NMR spectroscopic data andelemental analysis, and the results are given in Table 5 below.Single-crystal X-ray structures were obtained for three complexes of theseries.

[0083] Compound 1-b

[0084] A mixture of IrCl₃.nH₂O (54% Ir; 508 mg),2-(4-fluorophenyl)-5-trifluoromethylpyridine, compound kk (2.20 g),AgOCOCF₃ (1.01 g), and water (1 mL) was vigorously stirred under a flowof N₂ as the temperature was slowly (30 min) brought up to 185° C. (oilbath). After 2 hours at 185-190° C. the mixture solidified. The mixturewas cooled down to room temperature. The solids were extracted withdichloromethane until the extracts decolorized. The combineddichloromethane solutions were filtered through a short silica columnand evaporated. After methanol (50 mL) was added to the residue theflask was kept at −10° C. overnight. The yellow precipitate of thetris-cyclometalated complex, compound b, was separated, washed withmethanol, and dried under vacuum. Yield: 1.07 g (82%). X-Ray qualitycrystals of the complex were obtained by slowly cooling its warmsolution in 1,2-dichloroethane.

[0085] Compound 1-e

[0086] A mixture of IrCl₃.nH₂O (54% Ir; 504 mg),2-(3-trifluoromethylphenyl)-5-trifluoromethylpyridine, compound bb (1.60g), and AgOCOCF₃ (1.01 g) was vigorously stirred under a flow of N₂ asthe temperature was slowly (15 min) brought up to 192° C. (oil bath).After 6 hours at 190-195° C. the mixture solidified. The mixture wascooled down to room temperature. The solids were placed on a silicacolumn which was then washed with a large quantity of dichloromethane.The residue after evaporation of the filtrate was treated with methanolto produce yellow solid. The solid was collected and purified byextraction with dicilloromethane in a 25-mL micro-Soxhlet extractor. Theyellow precipitate of the tris-cyclometalated complex, compound e, wasseparated, washed with methanol, and dried under vacuum. Yield: 0.59 g(39%). X-Ray quality crystals of the complex were obtained from hot1,2-dichloroethane.

[0087] Compound 1-d

[0088] A mixture of IrCl₃.nH₂O (54% Ir; 508 mg),2-(2-fluorophenyl)-5-trifluoromethylpyridine, compound aa (1.53 g), andAgOCOCF₃ (1.01 g) was vigorously stirred under a flow of N₂ at 190-195°C. (oil bath) for 6 h 15 min. The mixture was cooled down to roomtemperature and then extracted with hot 1,2-dichloroethane. The extractswere filtered through a short silica column and evaporated. Treatment ofthe residue with methanol (20 mL) resulted in precipitation of thedesired product, compound d, which was separated by filtration, washedwith methanol, and dried under vacuum. Yield: 0.63 g (49%). X-Rayquality crystals of the complex were obtained fromdichloromethane/methanol.

[0089] Compound 1-i

[0090] A mixture of IrCl₃.nH₂O (54% Ir; 503 mg),2-(4-trifluoromethoxyphenyl)-5-trifluoromethylpyridine, compound ee(2.00 g), and AgOCOCF₃ (1.10 g) was vigorously stirred under a flow ofN₂ at 190-195° C. (oil bath) for 2 h 45 min. The mixture was cooled downto room temperature and then extracted with dichloromethane. Theextracts were filtered through a short silica column and evaporated.Treatment of the residue with methanol (20 mL) resulted in precipitationof the desired product, compound i, which was separated by filtration,washed with methanol, and dried under vacuum. The yield was 0.86 g.Additionally, 0.27 g of the complex was obtained by evaporating themother liquor and adding petroleum ether to the residue. Overall yield:1.13 g (72%).

[0091] Compound 1-q

[0092] A mixture of IrCl₃.nH₂O (54% Ir; 530 mg),2-(3-methoxyphenyl)-5-trifluoromethylpyridine (2.50 g), AgOCOCF₃ (1.12g), and water (1 mL) was vigorously stirred under a flow of N₂ as thetemperature was slowly (30 min) brought up to 185° C. (oil bath). After1 hour at 185° C. the mixture solidified. The mixture was cooled down toroom temperature. The solids were extracted with dichloromethane untilthe extracts decolorized. The combined dichloromethane solutions werefiltered through a short silica column and evaporated. The residue waswashed with hexanes and then recrystallized from1,2-dichloroethane-hexanes (twice). Yield: 0.30 g. ¹⁹F NMR (CD₂Cl₂, 20°C.), δ: −63 (s). ¹NMR (CD₂Cl₂, 20° C.), δ: 8.1 (1H), 7.9 (1H), 7.8 (1H),7.4 (11H), 6.6 (2H), 4.8 (3H). X-Ray quality crystals of the complex(1,2-dichloroethane, hexane solvate) were obtained from1,2-dichloroethane-hexanes. This facial complex wasorange-photoluminescent.

[0093] Compounds 1-a, 1-c, 1-f through 1-h, 1-i through 1-m, and 1-rwere similarly prepared. In the preparation of compound 1-j, a mixtureof isomers was obtained with the fluorine in either the R₆ or R₈position. TABLE 5 Analysis NMR Compound (calcd (found) (CD₂Cl₂, 25° C.)1-a C: 50.3 (50.1) ¹H: 6.8 (1H), 6.9 (1H), 7.0 (1H), 7.8 H: 2.5 (2.7)(2H), 7.95 (1H), 8.1 (1H) N: 4.9 (4.9) ¹⁹F: −63.4 Cl: 0.0 (0.2) 1-b C:47.4 (47.3) ¹H: 6.4 (1H), 6.75 (1H), 7.7 (1H), 7.8 H: 2.0 (2.1) (1H),7.95 (1H), 8.05 (1H) N: 4.6 (4.4) ¹⁹F: −63.4 (s); −109.5 (ddd) 1-c C:47.4 (47.2) ¹H: 6.6 (1H), 6.7 (1H), 6.9 (1H), 7.8 H: 2.0 (2.0) (1H), 8.0(1H), 8.6 (1H) N: 4.6 (4.5) ¹⁹F: −63.5 (s); −112.8 (ddd) 1-d C: 55.9(56.1) ¹H: 6.6 (2H), 6.8 (1H), 7.0 (1H), 7.6 H: 3.0 (3.2) (1H), 7.7(1H), 8.4 (1H) N: 5.9 (5.8) ¹⁹F: −115.0 (ddd) 1-e C: 44.1 (43.3) ¹H: 6.9(1H), 7.1 (1H), 7.8 (1H), 8.0 H: 1.7 (2.1) (2H), 8.2 (1H) N: 3.9 (3.6)¹⁹F: −63.0 (1F), −63.4 (1F) 1-f C: 50.4 (50.5) ¹H: 6.9 (1H), 7.1 (2H),7.6 (1H), 7.8 H: 2.5 (2.7) (1H), 7.9 (1H), 8.1 (1H) N: 4.9 (4.9) ¹⁹F:−62.4 1-g C: 55.9 (56.3) ¹H: 6.4 (1H), 6.7 (1H), 7.0 (1H), 7.6 H: 3.0(3.2) (1H), 7.7 (2H), 7.9 (1H) N: 5.9 (6.0) ¹⁹F: −112.6 (ddd) 1-h C:51.0 (45.2) ¹H: 6.8 (1H), 6.95 (1H), 7.05 (1H), 7.7 H: 2.1 (2.3) (1H),8.0 (1H), 8.9 (1H) N: 4.9 (4.2) ¹⁹F: −63.3 1-i C: 49.4 (49.3) ¹H: 3.6(3H), 6.3 (1H), 6.6 (1H), 7.7 H: 2.9 (2.8) (2H), 7.85 (1H), 7.95 (1H) N:4.4 (4.4) ¹⁹F: −63.2 1-j C: 47.4 (47.4) ¹H: 6.7 (m), 7.1 (m), 7.5 (m),7.6 (m), H: 2.0 (2.3) 7.7 (m), 8.0 (m), 8.2 (m) N: 4.6 (4.7) ¹⁹F: 8 sresonances (−63.0-−63.6) and 8 ddd resonances (−92.2-−125.5) 1-k C: 43.5(44.0) ¹H: 6.9 (1H), 7.15 (1H), 8.1 (1H); 8.3 H: 1.8 (2.1) (1H), 8.45(1H), 8.6 (1H) N: 8.5 (8.4) ¹⁹F: −62.9 1-l C: 42.2 (42.1) ¹H: 6.5 (1H),6.7 (1H), 7.75 (1H), 7.85 H: 16. (1.8) (1H), 8.0 (1H), 8.1 (1H) N: 3.8(3.7) ¹⁹F: −58.1 (1F), −63.4 (1F)

Example 3

[0094] This example illustrates the preparation of iridium complexes ofthe Second Formula IrL^(a)L^(b)L^(C) _(x)L′_(y)L″_(z) above,

[0095] Compound 1-n

[0096] A mixture of IrCl₃.nH₂O (54% Ir; 510 mg),2-(3-trifluoromethylphenyl)-quinoline (1.80 g), and silvertrifluoroacetate (1.10 g) was vigorously stirred at 190-195° C. for 4hours. The resulting solid was chromatographed on silica withdichloromethane to produce a mixture of the dicyclometalated complex andthe unreacted ligand. The latter was removed from the mixture byextraction with warm hexanes. After the extracts became colorless thehexane-insoluble solid was collected and dried under vacuum. The yieldwas 0.29 g. ¹⁹F NMR: −63.5 (s, 6F), −76.5 (s, 3F). The structure of thiscomplex was established by a single crystal X ray diffraction study.

[0097] Compound 1-o

[0098] A mixture of IrCl₃.nH₂O (54% Ir; 500 mg),2-(2-fluorophenyl)-3-chloro-5-trifluoromethylpyridine (2.22 g), water(0.3 mL), and silver trifluoroacetate (1.00 g) was stirred at 190° C.for 1.5 hours. The solid product was chromatographed on silica withdichloromethane to produce 0.33 g of a 2:1 co-crystallized adduct of thedicyclometalated aqua trifluoroacetato complex, compound 1-p, and theunreacted ligand. ¹⁹F NMR: −63.0 (9F), −76.5 (3F), −87.7 (2F), −114.4(1F). The co-crystallized phenylpyridine ligand was removed byrecrystallization from dichloromethane-hexanes. The structures of boththe adduct and the complex were established by a single crystal X-raydiffraction study.

Example 4

[0099] This example illustrates the preparation of an hydroxo iridiumdimer, having structure (VIII) above.

[0100] A mixture of IrCl₃.nH₂O (54% Ir; 510 mg),2-(4-fluorophenyl)-5-trifluoromethylpyridine (725 mg), water (5 mL), and2-ethoxyethanol (20 mL) was vigorously stirred under reflux for 4.5hours. After a solution of NaOH (2.3 g) in water (5 mL) was added,followed by 20 mL of water, the mixture was stirred under reflux for 2hours. The mixture was cooled down to room temperature, diluted with 50mL of water, and filtered. The solid was vigorously stirred under refluxwith 30 mL of 1,2-dichloroethane and aqueous NaOH (2.2 g in 8 mL ofwater) for 6 hours. The organic solvent was evaporated from the mixtureto leave a suspension of an orange solid in the aqueous phase. Theorange solid was separated by filtration, thoroughly washed with water,and dried under vacuum to produce 0.94 g (95%) of the iridium hydroxodimer (spectroscopically pure). ¹H NMR (CD₂Cl₂): −1.0 (s, 11H, IrOH),5.5 (dd, 2H), 6.6 (dt, 2H), 7.7 (dd, 2H), 7.9 (dd, 2H), 8.0 (d, 2H), 9.1(d, 2H). ¹⁹F NMR (CD₂Cl₂): −62.5 (s, 3F), −109.0 (ddd, IF).

Example 5

[0101] This example illustrates the preparation of bis-cyclometalatedcomplexes from an iridium dimer.

[0102] Compound 1-p

[0103] A mixture of the iridium hydroxo dimer (100 mg) from Example 4,ethyl acetoacetate (0.075 mL; 4-fold excess), and dichloromethane (4 mL)was stirred at room temperature overnight. The solution was filteredthrough a short silica plug and evaporated to give an orange-yellowsolid which was washed with hexanes and dried. The yield of the complexwas 109 mg (94%). ¹H NMR (CD₂Cl₂): 1.1 (t, CH₃), 3.9 (dm, CH₂), 4.8 (s,CH₃COCH), 5.9 (m), 6.7 (m), 7.7 (m), 8.0 (m), 8.8 (d). ¹⁹F NMR (CD₂Cl₂):−63.1 (s, 3F), −63.2 (s, 3F), −109.1 (ddd, IF), −109.5 (ddd). Analysis:Calcd: C, 44.9; H, 2.6; N, 3.5. Found: C, 44.4; H, 2.6; N, 3.3.

[0104] Compound 1-w

[0105] A solution of hydroxo iridium dimer from Example 4 (0.20 g) inTHF (6 mL) was treated with 50 mg of trifluoroacetic acid, filteredthrough a short silica plug, evaporated to ca. 0.5 mL, treated withhexanes (8 mL), and left overnight. The yellow crystalline solid wasseparated, washed with hexanes, and dried under vacuum. Yield (1:1 THFsolvate): 0.24 g (96%). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.2 (s, 3F),−76.4 (s, 3F), −107.3 (ddd, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 9.2 (br s,1H), 8.2 (dd, 1H), 8.1 (d, 1H), 7.7 (m, 1H), 6.7 (m, 1H), 5.8 (dd, 1H),3.7 (m, 2H, THF), 1.8 (m, 2H, THF).

[0106] Compound 1-x

[0107] A mixture of the trifluoroacetate intermediate, compound 1-w (75mg), and 2-(4-bromophenyl)-5-bromopyridine (130 mg) was stirred under N₂at 150-155° C. for 30 min. The resulting solid was cooled to roomtemperature and dissolved in CH₂Cl₂. The resulting solution was filteredthrough silica gel and evaporated. The residue was washed several timeswith warm hexanes and dried under vacuum to leave a yellow,yellow-photoluminescent solid. Yield: 74 mg (86%). ¹⁹F NMR (CD₂Cl₂, 20°C.), δ: −63.1 (s, 3F), −63.3 (s, 3F), −108.8 (ddd, 1F), −109.1 (ddd,1F). ¹HNMR (CD₂Cl₂, 20° C.), δ: 8.2 (s), 7.9 (m), 7.7(m), 7.0 (d), 6.7(m), 6.2 (dd), 6.0 (dd). The complex was meridional, with the nitrogensof the fluorinated ligands being trans, as confirmed by X-ray analysis.

Example 6

[0108] This example illustrates the preparation of iridium compounds ofthe Fifth Formula mer-Ir(L^(a))₃ above.

[0109] Compound 1-s

[0110] This complex was synthesized in a manner similar to compound 1-n.According to the NMR, TLC, and TGA data, the result was an approximately1:1 mixture of the facial and meridional isomers.

[0111] Compound 1-t

[0112] A mixture of IrCl₃.nH₂O (54% Ir; 0.40 g),2-(3,5-difluorophenyl)-5-trifluoromethylpyridine (1.40 g), AgOCOCF₃(0.81 g), and water (0.5 mL) was vigorously stirred under a flow of N₂as the temperature was slowly (30-40 min) brought up to 165° C. (oilbath). After 40 min at 165° C. the mixture solidified. The mixture wascooled down to room temperature. The solids were extracted withdichloromethane until the extracts decolorized. The combineddichloromethane solutions were filtered through a short silica columnand evaporated. The residue was thoroughly washed with hexanes and driedunder vacuum. Yield: 0.53 g (49%). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.55(s, 3F), −63.57 (s, 3F), −63.67 (s, 3F), −89.1 (t, 1F), −100.6 (t, 1F),−102.8 (dd, 1F), −118.6 (ddd, 1F), −119.3 (ddd, 1F), −123.3 (ddd, 1F).¹H NMR (CD₂Cl₂, 20° C.), δ: 8.4 (s), 8.1 (m), 7.9 (m), 7.6 (s), 7.5 (m),6.6 (m), 6.4 (m). The complex was meridional, as was also confirmed byX-ray analysis.

[0113] Compound 1-u

[0114] This complex was prepared and isolated similarly to compound 1-q,then purified by crystallization from 1,2-dichloroethane-hexanes. Theyield of the purified product was 53%. The complex is mer, as followsfrom the NMR data. ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.48 (s, 3F), −63.52(s, 6F), −105.5 (ddd, 1F), −105.9 (ddd, 1F), −106.1 (ddd, 1F), −107.4(t, 1F), −107.9 (t, 1F), −109.3 (t, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 8.6(m), 8.3 (s), 8.2 (s), 8.1 (m), 7.9 (m), 7.6 (m), 6.6 (m), 6.4 (m), 6.0(m), 5.8 (m).

[0115] Compound 1-v

[0116] This mer-complex was prepared in a manner similar to compound1-w, using the trifluoroacetate dicyclometalated intermediate, compound1-x, and 2-(4-fluorophenyl)-5-trifluoromethylpyridine. ¹⁹F NMR (CD₂Cl₂,20° C.), δ: −63.30 (s, 3F), −63.34 (s, 3F), −63.37 (s, 3F), −108.9 (ddd,1F), −109.0 (ddd, 1F), −109.7 (ddd, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ:8.3-7.6 (m), 6.7 (m), 6.6 (dd), 6.3 (dd), 6.0 (dd). Thisyellow-luminescent merisional complex isomerised to the greenluminescent facial isomer, compound 1-b, upon sublimation at 1 atm.

Example 7

[0117] This example illustrates the formation of OLEDs using the iridiumcomplexes of the invention.

[0118] Thin film OLED devices including a hole transport layer (HTlayer), electroluminescent layer (EL layer) and at least one electrontransport layer (ET layer) were fabricated by the thermal evaporationtechnique. An Edward Auto 306 evaporator with oil diffusion pump wasused. The base vacuum for all of the thin film deposition was in therange of 10-6 torr. The deposition chamber was capable of depositingfive different films without the need to break up the vacuum.

[0119] An indium tin oxide (ITO) coated glass substrate was used, havingan ITO layer of about 1000-2000 Å. The substrate was first patterned byetching away the unwanted ITO area with 1N HCl solution, to form a firstelectrode pattern. Polyimide tape was used as the mask. The patternedITO substrates were then cleaned ultrasonically in aqueous detergentsolution. The substrates were then rinsed with distilled water, followedby isopropanol, and then degreased in toluene vapor for ˜3 hours.

[0120] The cleaned, patterned ITO substrate was then loaded into thevacuum chamber and the chamber was pumped down to 10⁻⁶ torr. Thesubstrate was then further cleaned using an oxygen plasma for about 5-10minutes. After cleaning, multiple layers of thin films were thendeposited sequentially onto the substrate by thermal evaporation.Finally, patterned metal electrodes of Al were deposited through a mask.The thickness of the film was measured during deposition using a quartzcrystal monitor (Sycon STC-200). All film thickness reported in theExamples are nominal, calculated assuming the density of the materialdeposited to be one. The completed OLED device was then taken out of thevacuum chamber and characterized immediately without encapsulation.

[0121] A summary of the device layers and thicknesses is given in Table6. In all cases the anode was ITO as discussed above, and the cathodewas Al having a thickness in the range of 700-760 A. In some of thesamples, a two-layer electron transport layer was used. The layerindicated first was applied adjacent to the EL layer. TABLE 6 HT layerEL layer ET layer Sample (Thickness, Å) (Thickness, Å) (Thickness, Å)Comparative MPMP (528) Ir(ppy)₃ DDPA (106) + (408) Alq₃ (320)  1 MPMP(520) Compound 1-b DDPA (125) + (499) Alq₃ (365)  2 MPMP (541) Compound1-b DDPA (407) (580)  3 MPMP (540) Compound 1-e DDPA (112) + (499) Alq₃(340)  4 MPMP (525) Compound 1-k DDPA (106) (406) Alq₃ (341)  5 MPMP(570) Compound 1-i DDPA (107) + (441) Alq₃ (339)  6 MPMP (545) Compound1-j DDPA (111) + (462) Alq₃ (319)  7 MPMP (643) Compound 1-g DDPA(112) + (409) Alq₃ (361)  8 MPMP (539) Compound 1-f DDPA (109) + (430)Alq₃ (318)  9 MPMP (547) Compound 1-a DDPA (105) + (412) Alq₃ (300) 10MPMP (532) Compound 1-h DDPA (108) + (457) Alq₃ (306) 11 MPMP (603)Compound 1-d DDPA (111) + (415) Alq₃ (303) 12 MPMP (551) Compound 1-cDDPA (106) + (465) Alq₃ (313) 13 MPMP (520) Compound 1-l DDPA (410)(405) 14 MPMP (504) Compound 1-b DDPA (393) (400) 15 MPMP (518) Compound1-b DDPA (418) (153) 16 MPMP (556) Compound 1-m DDPA (430) (416) 17 MPMP(520) Compound 1-n DDPA (420) (419) 18 MPMP (511) Compound 1-o DDPA(413) (412) 19 MPMP (527) Compound 1-p DDPA (412) (425) 20 MPMP (504)Compound 1-q DPA (407) (417) 21 MPMP (525) Compound 1-t DPA (416) (419)22 MPMP (520) Compound 1-u DPA (405) (421)

[0122] The OLED samples were characterized by measuring their (1)current-voltage (I-V) curves, (2) electroluminescence radiance versusvoltage, and (3) electroluminescence spectra versus voltage. Theapparatus used, 200, is shown in FIG. 2. The I-V curves of an OLEDsample, 220, were measured with a Keithley Source-Measurement Unit Model237, 280. The electroluminescence radiance (in the unit of Cd/m²) vs.voltage was measured with a Minolta LS-110 luminescence meter, 210,while the voltage was scanned using the Keithley SMU. Theelectroluminescence spectrum was obtained by collecting light using apair of lenses, 230, through an electronic shutter, 240, dispersedthrough a spectrograph, 250, and then measured with a diode arraydetector, 260. All three measurements were performed at the same timeand controlled by a computer, 270. The efficiency of the device atcertain voltage is determined by dividing the electroluminescenceradiance of the LED by the current density needed to run the device. Theunit is in Cd/A.

[0123] The results are given in Table 7 below: TABLE 7ElectroluminescentProperties of Iridium Compounds Peak Efficiency atPeak Approximate Radiance, peak radiance, efficiency, Peak Wave- SampleCd/m2 Cd/A Cd/A lengths, nm Comparative  540 0.39 0.48 522 at 22 V  11400 3.4 11 525 at 21 V  2 1900 5.9 13 525 at 25 V  3  830 1.7 13.5 525at 18 V  4    7.6 0.005 0.13 521 at 27 V  5  175 0.27 1.8 530, 563 at 25V  6  514 1.5 2.2 560 at 20 V  7  800 0.57 1.9 514 at 26 V  8 1200 0.612 517 at 28 V  9  400 1.1 4 545 at 18 V 10  190 2.3 3.3 575 at 16 V 111150 1.2 3.8 506, 526 at 25 V 12  340 0.49 2.1 525 at 20 V 13  400 3 5520 at 21 V 14 1900 5 9 525 15 2500 6 11 525 16  100 0.17 0.2 560 at 27V 17    3.5 0.005 0.014 575 at 28 V 18  30 0.08 0.16 590 at 26 V 19 20006 8 532 at 21 V 20  350 0.60 1.6 595 at 26 V 21 1200 5 545 at 22 V 22 80 1 540 at 19 V

[0124] The peak efficiency is the best indication of the value of theelectroluminescent compound in a device. It gives a measure of how manyelectrons have to be input into a device in order to get a certainnumber of photons out (radiance). It is a fundamentally importantnumber, which reflects the intrinsic efficiency of the light-emittingmaterial. It is also important for practical applications, since higherefficiency means that fewer electrons are needed in order to achieve thesame radiance, which in turn means lower power consumption. Higherefficiency devices also tend to have longer lifetimes, since a higherproportion of injected electrons are converted to photons, instead ofgenerating heat or causing an undesirable chemical side reactions. Mostof the iridium complexes of the invention have much higher peakefficiencies than the parent-tris(2-phenylpyridine) iridium complex.Those complexes with lower efficiencies may also find utility asphosphorescent or photoluminescent materials, or as catalysts, asdiscussed above.

What is claimed is:
 1. An organic electronic device comprising anemitting layer wherein at least 20% by weight of the emitting layercomprises at least one compound having a formula below:IrL^(a)L^(b)L^(c) _(x)L′_(y)L″_(z), where: x=0 or 1, y=0, 1 or 2, andz=0 or 1, with the proviso that: x=0 or y+z=0 and when y=2then z=0; L′=abidentate ligand or a monodentate ligand, and is not a phenylpyridine,phenylpyrimidine, or phenylquinoline; with the proviso that: when L′ isa monodentate ligand, y+z=2, and when L′ is a bidentate ligand, z=0;L″=a monodentate ligand, and is not a phenylpyridine, andphenylpyrimidine, or phenylquinoline; and L^(a), L^(b) and L^(c) arealike or different from each other and each of L^(a), L^(b) and L^(c)has structure (I) below:

wherein: adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring, at least one of R₁-R₈ is selected from F,C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, orBr, and A=C or N, provided that when A=N, there is no R₁.
 2. The deviceof claim 1 wherein x=1, y=0, and z=0.
 3. The device of claim 2 whereinA=C and none of R₁-R₈ is selected from nitro.
 4. The device of claim 1wherein R₃ is CF₃.
 5. The device of claim 4 wherein at least one ofR₅-R₈ is selected from F, C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X,where n=1-6 and X=H, Cl, or Br.
 6. The device of claim 2 wherein A=C,R₃=CF₃, R₇=F, and R₁, R₂, R₄-R₆ and R₈=H.
 7. The device of claim 2wherein A=C, R₃ and R₆=CF₃, and R₁, R₂, R₄, R₅, R₇ and R₈=H.
 8. Thedevice of claim 2 wherein A=C, R₃=CF₃, R₆ and R₈=F, and R₁, R₂, R₄, R₅,and R₇=H.
 9. The device of claim 1 wherein x=0 and y=1 having astructure (VI) below:


10. An organic electronic device comprising an emitting layer whereinthe emitting layer comprises a diluent and less than 20% by weight of atleast one compound that has a formula below: IrL^(a)L^(b)L^(c), where:L^(a), L^(b) and L^(c) are alike or different from each other and eachof L^(a), L^(b) and L^(c) has structure (I) below:

wherein: adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring, at least one of R₁-R₈ is selected from F,C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, orBr, and A=C or N, provided that when A=N, there is no R₁.
 11. The deviceof claim 10 wherein the diluent is selected from poly(N-vinylcarbazole), polysilane, 4,4′-N,N′-dicarbazole biphenyl, and tertiaryaromatic amines.
 12. The device of claim 1, further comprising a holetransport layer selected fromN,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis-(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)-benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane(DCZB), N,N,N′,N′-tetrakis(4-methylphenyl)-(1, I′-biphenyl)-4,4′-diamine(TTB), porphyrinic compounds, and combinations thereof.
 13. The deviceof claim 1, further comprising an electron transport layer selected fromtris(8-hydroxyquinolato)aluminum,2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA),4,7-diphenyl-1,10-phenanthroline (DPA),2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD),3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ), andcombinations thereof.
 14. A compound having a formula selected fromfac-Ir(L)₃, mer-Ir(L)₃, and combinations thereof, where L is selectedfrom group 1-a through 1-m and 1-q through 1-v, as shown in Table 1, andhas structure (I) below:

wherein: adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring, |at least one of R₁-R₈ is selected from F,C_(n)F_(2n+1) , OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, orBr, and A=C or N, provided that when A=N, there is no R₁.
 15. A compoundhaving a structure selected from structures (IV), (V), (VI), (IX) and(X) below: F₃C Ir CF₃ (IV)


16. An organic electronic device comprising an emitting layer thatcomprises a compound selected from the following (i) and (ii): (i) acompound having a formula selected from fac-Ir(L)₃, mer-Ir(L)₃, andcombinations thereof, where L is a group selected from 1-a through 1-mand 1-q through 1-v, as shown in Table 1 and has structure (I) below:

wherein: adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring, at least one of R₁-R₈ is selected from F,C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, orBr, and A=C or N, provided that when A N, there is no R₁; (ii) acompound having one of structures (IV), (V), (VI), (IX), and (X) below:


17. The device of claim 16 wherein the emitting layer further comprisesa diluent.
 18. The device of claim 17 wherein the diluent is selectedfrom poly(N-vinyl carbazole), polysilane, 4,4′-N,N′-dicarbazolebiphenyl, and tertiary aromatic amines.
 19. A compound selected fromcompounds 2-a through 2-aa as shown in Table 2, having structure (II)below:

wherein: R₉ is H; adjacent pairs of R₁-R₄ and R₅-R₈ can be joined toform a five- or six-membered ring; at least one of R₁-R₈ is selectedfrom F, C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H,Cl, or Br, and A=C or N, provided that when A=N, there is no R₁.
 20. Acompound having structure (III) below:

wherein R₁₇=CF₃ and R₁₀-R₁₆ and R₁₈-R₂₀=H.
 21. A compound havingstructure VII below:

wherein: B=H, CH₃, or C₂H₅; L^(a), L^(b), L^(c), and L^(d) are the sameor different from each other; and each of L^(a), L^(b), L^(c), and L^(d)has structure (I) below:

wherein: adjacent pairs of R₁-R₄ and R₅-R₈ can be joined to form a five-or six-membered ring, at least one of R₁-R₈ is selected from F,C_(n)F_(2n+1a), OC_(n)F_(2n+1), and OCF₂X, where n=1-6 and X=H, Cl, orBr, and A=C or N, provided that when A=N, there is no R₁.
 22. Thecompound of claim 21 wherein: L^(a)=L^(b)=L^(c)=L^(d); B=H; R₃=CF₃;R₇=F; R₁, R₂, R₄-R₆ and R₈=H.